Issue using SmartText in Description field in Case Management

Summary:

We've created SmartTexts to be used in Case Management in the Description field, it works fine in the Create Case Layout but not in the Edit Case Layout. The SmartText is created using plain text so the HTML tick box is unchecked, the user has the correct privileges and I've checked the field templates match in VBS. Has anyone else come across this issue and if so been able to fix it?

Content (please ensure you mask any confidential information):

SmartText set up

Edit Case Layout, I've typed '#' and selected the SmartText but it just shows the title and doesn't populate the rest of the Smart Text